HTR4 and chronic obstructive pulmonary disease: Given the genetic association data and potential clinical significance of the HTR4 gene in respiratory physiology and pathophysiology, we sought to i) investigate the expression profile of HTR4 in both adult and fetal lung tissue and in lung tissue from individuals with COPD, ii) define the gene structure and iii) using the ENCODE dataset, investigate the potential functional mechanisms underlying select key HTR4 SNPs associated with lung function.